Lubricating oil and lubrication therewith



v Patented Oct. 22, l

' UNITED. STATEsI-MmNr OFFICE I 2,218.61; wsalcs'rme ommnwnnrcsnos jArthur Walther Lewis, Elizabeth, 1., assignor to Tide Water AssociatedOil Company, Bayonne, N. 1., a corporation of Delaware,

' No Drawing. Application with 11.

Serial No. 131,45:

7 10 Claims. (cuss-s) This invention relates to lubricants intended forservice in the lubrication of internal combustion engines. The inventionmore particularly is concerned with lubricating or motor oils of minveral hydrocarbon origin which are normally corrosive toward bearingmetal alloys of the char; acter of cadmium-silver, cadmium-nickel orcop'- per-lead, as well as thosebearing metals of exceptionally highlead content (of the order of 75% to 99%) wherein minor proportions ofalloying metals'impart unusual hardness to the alloy; and has, for animportant objective,' the inhibition or prevention of deterioration ofsuch hearing metal in service by the corrosive action of the lubricantthereon. Y

Engine bearings comprising or surfaced with cadmium-silver, high-lead"or like alloys now are frequently employed in lieu of the more usualBabbitt metal hearings, in order to cope with extreme service conditionsof friction and temperature. These conditions are the consequences ofmodern developments in internal combustion engines making available highsustained speeds and requiring bearings formed of metals or alloyshaving greater resistance to wear, and further characterized by highermelting points necessary to prolonged life under the extreme thermalconditions existing during operationof the engine. Temperatures at thebearing surfaces during operation are, or maybe, much higher in are ofthe character generally regarded as superior lubricants by conventionalcriteria.

I little is known concerning the nature of the corrosive action oritscauses; but in general it tests indicative of the tendency towarddeterioration of the oil itself in service,does not appear. to havereliable correlation with-the tendency of the oil to corrode bearing.surfaces. It is possible that the high bearing surface temperaturesexisting. under service conditions with the new bearingsv may be afactor inoccasioningthe observed deleterious effect of motoroilsthereupon. It would appear. also, that the problem of bearing corrosion,with which the present invention is parlubricant deterioration per se,since" oils characterized by long life and good stability inconventional tests may, and frequently do, prove to befithe" mostcorrosive in bearing corrosion tests. No 'th'eory in explanation of theobserved corrosive action or the prevention thereof, as herein proposedaccording to the invention, is intended to'be relied upon. J

According to the present invention, it has now been found that thecorrosive effect of lubricating oils upon bearing surfaces of thecharacter referred to above may be avoided in novel and eilebtive mannerby incorporating with such oils particular compounds having a retardingor inhibiting'efiect in respect of such corrosion. More specifically,the invention arises from the discovery that acompoundcomprising adiamino of the character or poly-aryl methane effects a very beneficialretardation ofthe corrosive action of internal combustion enginelubricating oils upon cadmiumsilver, cadmium-nickel, copper-lead,"highlead and like bearing metal alloys.

It is, thereore, an important object of the present inventon to inhibitor retard the corrosive deterioration of these and like bearing metala1- loysin automotive service by providing a lubricant thereforcomprising a refined mineral hydrocarbon oil having incorporatedtherewith a diamino poly-aryl niethane in small but effectiveproportion. Likewise, it is an. object of the inhas been observed thatmotoroils derived from selected crudes predominantly paraflinic inorigin, as well as those oils fr0m these or other 50 crudes which havebeen improved bytreatment with selective solvents, exhibit a markedtend-.

rency toward corrosion'of the'bearings in question,,aithoughbyothertokensthe lubricant is of "superior quality. Oxidation stability, asindis5 cated by'sludge or acid formation in conventional rosioninhibiting proportions.

vention to improve, and to prepare improved, motor oils of petroleumorigin byincorporating l ticularly'concerned, contrasts with problems oftherein a diamino poly-aryl methane in corg The provision of aninhibitor e'flective for such purpose and comprising a'compound asaforementioned-naturally is a major objective.

Viewed in another aspect the invention may be regarded 'as encompassinga novel method of lubricating bearing metal surface, of the character ofcadmium-silver, cadmium-nickel, co pper-lead, high-lead or like alloys,by applying thereto a film of lubricantxc'omprising mineral hydrocarbonoilhavirg incorporated therewith a invention to its intended service,will be of a character generally regarded as of superior grade andrefining. Thus, the invention finds particular utility in makingpossible the beneficial use of such oils by avoiding deleteriousconsequences otherwise encountered when no preventive measures are takenagainst the corrosive deterioration of bearing metal alloys ashereinbefore referred to. It will be understood, however, that theinvention contemplates no limitation in this respect, and that themethod of lubrication herein described may be practiced in conjunctionwith mineral hydrocarbon lubricating oils taken as a broad class andregardless of origin.

Solubility of a diamino poly-aryl methane in mineral hydrocarbon oil ofmotor lubricating 011 character is limited, but the proportion necessaryto accomplish the objects of the present invention is well within thelimits of solubility. It suflices, therefore, simply to dissolve adiamino poly-aryl methane (if desired with moderate application of heatto facilitate solution) in motor oil intended for service in internalcombustion engines in order toprepare for the lubrication thereofaccording to the invention. Proportions of less than 0.2% by weight ofthe inhibitor dissolved in motor oil are shown hereinafter to beinhibitive of the corrosion normally attending the use of manylubricating oils with hearing metals of the type comprisingcadmium-silver and like alloys. The stated percentage is not intended asa limitation upon the contemplated scope and practice of the invention,as obviously the inhibitor may be, and is intended to be, employed inany corrosion inhibiting proportion.

The tendency of motor oils to corrode bearings of the character inquestion may be determined by a convenient test which affords a readymethod of obtaining a comparative evaluation of motor oils in thelaboratory. In this test method a group of bearings, ordinarilyincluding at least one each of several of the newer bearing metal alloys(viz: cadmium-silver, cadmium-nickel and copper-lead) is supported in achamber in which air may circulate and the bearing surfaces are exposedfor a period of 22 hours to a stream of oil sprayed under pressurecontinuously upon the corrodible area. The oil is maintained at atemperature of approximately 335 F. and the spray is so directed as todisperse the oil over the surfaces of the bearings. Means are providedfor re-circulating the sprayed oil so that a given quantity is used fora given test, thus simulating service conditions in an engine.' Themeasure of corrosion is taken as the loss in weight of the bearing perunit of exposed corrodible surface;

The test method described above is carried but in the familiar Underwoodcorrosion apparatus supplied by the Scientific Instrument Company ofDetroit, Michigan, in accordance with General Motors specifications. aResults obtained utilizing the foregoing test for comparative evaluationof motor oils with and without an inhibitor according to the inventionprovide specific illustra ion of thevalue and inhibiting effectivenessof a diamino poly-aryl methane. The oil used for the test was an S. A.E. 20 motor oil comprising a blend of well refined parafiinic basestocks and having an A. P. I. gravity of 30.1, Saybolt viscosity at F.of about 300 seconds, Saybolt viscosity at 210 F. of 54 seconds andflash point of 425 F. In view of the limited solubilit of diaminopoly-aryl methane in motor oils, a saturated solution was prepared bystirring into one portion of the oil an amount of inhibitor equivalentto 0.2% by weight based on the oil, permitting the excess to settle anddraining off a saturated solution. The oil was warmed to facilitatedissolving the compound therein. During each run cadmiumsilver,cadmium-nickel and copper-lead bearings all were present; andcomparative losses in weight per square decimeter due to corrosion wereobserved as follows for the respective bearings:

Tnsr I.P,P' diamino diphenyl methane Oil Oil plus blank Bearinginhibitor Grams Grams Cadmium-silver... 5. 0 l. l Cadmium-nickeL 3. 8 2.2 Copper-lead 1. 5 0. l I. -7 Tas'r II.-P,P diamino trz'phenyl methaneOil Oil plus Bearmg blank inhibitor Cadmium-silver 7. No loss.Cadmium-nickel 10. Do. Copper-lead l. 1 Do.

In Test I the used oil from the blank run had a neutralization number of4.3 milligrams KOH per gram of oil, and the used oil from the inhibitorcontaining run had a neutralization number of 3.7 milligrams KOH- pergram of oil. From this it would appear that p,p diamino diphenylmethane, while effective to retard bearing corrosion, did not apparentlyexert any marked action in respect of retarding concurrent oildeterioration per se. The results secured in Test II differed from thosein Test I in this respect; .I-Iere the neutralization number of the usedoil from the blank run was 7.56 milligrams KOH per gram of oil while theused oil from the inhibitor containing run was but 1.90milligrams KOHper gram of oil.

Actual operation of an internal combustion engine lubricated accordingto the invention likewise demonstrates the eflicacy of a diaminopolyaryl methane as an inhibitor of bearing corrosion. Thetests were runin an eight cylinder automobile engine equipped with connecting-rodbearings of the newer type exemplified by the alloys mentioned above;and operated under carefully controlled conditions duplicated insuccessive runs with and without inhibitor present in the lubricatingoil. I New bearings carefully weighed wereused for each run, and eachset comprised alternate cadmium-silver and copperlead bearingsrespectively. Operating conditions included an engine speed of 2850 R.P. M. under a load of 50 brake horsepower and a running period of 15hours. this being the equivalent of 768 miles travel at a speed of 51.2miles per hour. crankcase oil temperature was maintained at .300" F. andwater temperature at 200 F. The oil consequently was subjected tolubricating service far more severe than that normally to be encounteredin ordinary automotive use. Atthe end of each run the hearings wereremoved and again weighed, the loss in weight giving a measure ofcorrosion caused by the lubricant.

Tested in an engine under the foregoing conditions an S. A. E. 20 motoroil, of the character and specifications used in the laboratoryevaluations reported earlier herein, gave the following results:

. Milligramslosin weight per bearing Inhibitor .Cd-Ag Ou-Pb None(average of a number of runs) 3510+ 450+ Sat. sol'n. (less than 0.2%)p,p' diamino triphenyl methane v Q The evidence presentedby all the foreoing.

data ,clearly shows the operative significance of J the foregoing enginetest of accentuated severity illustrated specifically with reference toa partictions '01 a diamino poly-aryl methane eifective to retardcorrosive deterioration of such by said oil.

2. The method of lubricating bearing surfaces in internal combustionengines, which bearing surfaces comprise an alloy having substantiallythe corrosion susceptibility characterizing cadmium-silver,cadmium-nickel, copper-lead and high-lead alloys, which consists inapplying to said bearing surfaces lubricant comprising mineralhydrocarbon oil normally tending corrode said surfaces and havingincorporated therein corrosion inhibiting proportions of a diaminopoly-aryl methane eifective to retard corrosive deterioration of suchbearings by said oil.

3. In the lubrication of bearing surfaces, at least one of which isformed of an alloy having substantially the corrosion susceptibilitycharacterizing cadmium-silver, cadmium-nickel, copper-lead andhigh-lead" alloys, with mineral hydroc'arbon oil normally tending tocause substantial and rapid corrosion thereof, the method of inhibitingsuch corrosion, which comprises incorporating with said oil corrosioninhibiting proportions of a diamino poly-aryl methane effective toretard corrosive deterioration of such bearings by said oil.

4. The method of claim 3, further characterized in that said diaminopoly aryl methane is a diamino poly-phenyl methane. l

5. The method of claim 3, further characterized in that said diaminopoiy-aryl methane is a diamino diphenyl methane.

6. The method of claim 3, further characterized in that saiddiaminopoly-aryl methane is a diamino triphenyl methane.

7. Mineral oil composition, comprising a hydrocarbon lubricating oil ofmotor oil character normally tending to corrode bearing metal havingsubstantially the corrosion susceptibility characterizing.cadmium-silver, cadmium-nickel, copper-lead and "high-lead alloys whencontinuously applied to the surface thereof for an extended period oftime at an oil temperature of 300 F. or above, and a diamino triphenylmethane in corrodon inhibiting proportions.

8. Mineral oil composition, comprising a hydrocarbon lubricating oil ofmotor oil character normally tending to corrode bearing metal havingsubstantially the corrosion susceptibility characterizingcadmium-silver, cadmium-nickel, copper-lead and "high-lead alloys whencon-- tinuously applied to the surface thereof for an extended period oftime at an oil temperature of 300 or aboverand p,p' diamino triphenylwith said oil in corrosion inhibiting proportions.

10. Mineral oil composition, comprising a hy-.

drocarbon lubricating oil of a character normally tending to corrodebearing metal having substantially the corrosion susceptibilitycharacterizing cadmium-silver, cadmium-nickel, and copper-lead alloyswhen continuously applied to the surface thereof imder serviceconditions, and p,p' diamino triphenyl methane incorporated with saidoil in corrosion inhibiting proportions.

ARTHUR WALTEER LEWIS.

